Not hugely useful. Going to the real browser is almost as quick and way easier to debug, inspect etc. It also failed to load a URL using localhost – having to use absolute URL each time could be a pain

I was puttering around with cross-browser rotated text earlier this week, and browserlab came in quite handy to compare renderings across browsers and platforms. The onion layering was very convenient to make sure the different methods of rotating text (SVG for most browsers, writing-mode for IE) produced exactly the same results. I agree it’s not a useful tool for app testing, but then it’s meant for the design crowd. By the way, for the curious: http://sebrechts.net/demo/collapsedtitle/collapsedtitle.html